It’s Berlin: 1920s. The clatter of cups on saucers. The wafting aroma of coffee. The buzz of eager students debating the hot new theories of Sigmund Freud and Albert Einstein. Kurt Lewin, a psychology professor, is meeting a student of his, Bluma Zeigarnik.

I’m sitting cross-legged on the sofa, feeling my breath flow in through my nostrils. As it fills with air, my belly strains outward against the waistband of my skirt. Unbidden, a thought comes to mind: Oh, I forgot…